Drought response strategies define the relative contributions of hydraulic dysfunction and carbohydrate depletion during tree mortality
Article first published online: 10 DEC 2012
© 2012 CSIRO. New Phytologist © 2012 New Phytologist Trust
Volume 197, Issue 3, pages 862–872, February 2013
How to Cite
Mitchell, P. J., O'Grady, A. P., Tissue, D. T., White, D. A., Ottenschlaeger, M. L. and Pinkard, E. A. (2013), Drought response strategies define the relative contributions of hydraulic dysfunction and carbohydrate depletion during tree mortality. New Phytologist, 197: 862–872. doi: 10.1111/nph.12064
- Issue published online: 7 JAN 2013
- Article first published online: 10 DEC 2012
- Manuscript Accepted: 20 OCT 2012
- Manuscript Received: 2 AUG 2012
- Australian Government's Department of Agriculture, Forestry and Fisheries
- carbon limitation;
- drought mortality;
- hydraulic conductance;
- hydraulic failure;
- nonstructural carbohydrates;
- plant strategy
- Plant survival during drought requires adequate hydration in living tissues and carbohydrate reserves for maintenance and recovery. We hypothesized that tree growth and hydraulic strategy determines the intensity and duration of the ‘physiological drought’, thereby affecting the relative contributions of loss of hydraulic function and carbohydrate depletion during mortality.
- We compared patterns in growth rate, water relations, gas exchange and carbohydrate dynamics in three tree species subjected to prolonged drought.
- Two Eucalyptus species (E. globulus, E. smithii) exhibited high growth rates and water-use resulting in rapid declines in water status and hydraulic conductance. In contrast, conservative growth and water relations in Pinus radiata resulted in longer periods of negative carbon balance and significant depletion of stored carbohydrates in all organs. The ongoing demand for carbohydrates from sustained respiration highlighted the role that duration of drought plays in facilitating carbohydrate consumption.
- Two drought strategies were revealed, differentiated by plant regulation of water status: plants maximized gas exchange, but were exposed to low water potentials and rapid hydraulic dysfunction; and tight regulation of gas exchange at the cost of carbohydrate depletion. These findings provide evidence for a relationship between hydraulic regulation of water status and carbohydrate depletion during terminal drought.